Cascara sagrada is a plant-based laxative used primarily to relieve occasional constipation. The dried bark of this Pacific Northwest tree stimulates the colon to move stool along more quickly, and it has been used for this purpose for centuries. Native Americans considered it “sacred bark,” which is where its Spanish name comes from. Today it’s sold as a dietary supplement, though its regulatory status has shifted significantly over the past two decades.
How It Works as a Laxative
The active compounds in cascara sagrada bark are anthraquinone derivatives and their glucosides, collectively called cascarosides. Supplement labels typically standardize the bark to contain 25 to 30% of these active compounds. When you take cascara, these compounds travel largely unabsorbed through your digestive tract until they reach the colon, where they do two things: they irritate the colon wall to trigger the wave-like muscle contractions that push stool forward, and they block the colon from reabsorbing water and electrolytes. The result is softer, bulkier stool that moves through more quickly.
This makes cascara a stimulant laxative, placing it in the same category as senna. It’s not a fiber supplement or stool softener. It actively forces the colon to contract, which is why it works relatively fast but also why it carries more risks with prolonged use.
Common Uses
The primary use is short-term relief of occasional constipation. Some people turn to cascara when dietary changes, increased water intake, or gentler options like fiber supplements haven’t worked. It’s available in capsule form, as a tea, or as a liquid extract. The typical capsule dose is 300 mg taken once daily, and the aromatic fluid extract dose is about 1 ml.
Cascara is not intended for chronic or long-term constipation management. The general guidance is to avoid taking it for more than six consecutive days. If constipation persists beyond that window, the underlying cause likely needs a different approach.
FDA Regulatory Status
Until 2002, cascara sagrada was approved as an over-the-counter laxative ingredient in the United States. That changed when the FDA requested data on potential cancer-causing effects and no manufacturers submitted the required studies. Without evidence to confirm its safety, the FDA ruled in November 2002 that cascara sagrada could no longer be marketed as a recognized safe and effective OTC drug.
This doesn’t mean cascara disappeared from store shelves. It simply shifted categories. Companies can still sell it as a dietary supplement, which falls under different (and less stringent) regulations. You’ll find cascara in the supplement aisle rather than the medicine aisle, and the products cannot legally claim to treat constipation as a drug would.
Side Effects and Risks
Short-term use commonly causes abdominal cramping, diarrhea, and electrolyte imbalances. Because cascara prevents the colon from reabsorbing water and minerals, you lose sodium, potassium, magnesium, and zinc with each dose. For most healthy adults using it briefly, these losses are minor. But they can become significant if use continues.
Chronic use of stimulant laxatives like cascara can also reduce absorption of fat-soluble vitamins (A, D, E, and K) and calcium. The faster stool moves through your intestines, the less time your body has to pull nutrients from food.
Melanosis Coli
One distinctive effect of long-term anthraquinone laxative use is melanosis coli, a condition where the inner lining of the colon turns dark brown or black. It sounds alarming, but it’s benign and causes no symptoms on its own. Most people only discover it incidentally during a colonoscopy. The discoloration is reversible: once you stop taking the laxative, your colon returns to its normal color within six to twelve months.
Who Should Avoid It
Several groups should not use cascara sagrada at all. Pregnant and breastfeeding women should avoid it because the active compounds can cross into breast milk and cause diarrhea in nursing infants. Children should not take it due to the risk of dehydration and dangerously low potassium levels.
People with chronic intestinal conditions also need to steer clear. This includes Crohn’s disease, ulcerative colitis, irritable bowel syndrome, appendicitis, stomach ulcers, and any unexplained abdominal pain. Stimulating already-inflamed or compromised intestinal tissue can worsen these conditions significantly.
Interactions With Other Medications
The biggest concern is combining cascara with medications that also affect fluid and electrolyte balance. If you take diuretics (water pills), the fluid and mineral losses from both can stack up, raising the risk of dehydration, dangerously low potassium, muscle cramps, dizziness, and abnormal heart rhythms. Low potassium is particularly dangerous because it affects heart function.
This interaction extends to any medication sensitive to potassium levels, including certain heart medications. If you’re taking prescription drugs that influence electrolytes, combining them with a stimulant laxative without medical guidance creates real risk. Signs of trouble include unusual fatigue, muscle weakness, cramping, lightheadedness, and a rapid or irregular heartbeat.